The arrangement will effectively insure the scheme against its liabilities and guarantee payments to members "at least equal in value" to the compensation they would receive under the Pension Protection Fund (PPF), in the event of the company failing. It is not known what fee Rothesay will receive for insuring the scheme.

The deal comes just months after the Pensions Regulator gave permission for Uniq to hand the majority of its shares to the pension scheme.

The company agreed to transfer 90.2pc of its equity to 21,000 pensioners under a "deficit for equity swap" because the scheme's £473m deficit dwarfed the company's market capitalisation of £5.6m.

Uniq has since been sold to sandwich maker Greencore for £113m. Chris Martin, chairman of the Uniq pension scheme said: "Since the deficit-for-equity swap earlier this year, our main objective has been to secure – with an insurance company – benefits at least equal in value to PPF compensation with the possibility of a top-up above that level."

Companies such as Rothesay Life and Pension Corporation specialise in buy-out deals, where it takes over pension scheme assets and liabilities, and buy-in deals, where it writes an insurance policy against liabilities.

JLT Pension Capital Strategies has estimated that £3.85bn worth of deals had been sealed in nine months to the end of September. "As soaring debt and increasing liabilities become more of an issue for pensions schemes, trustees are seeking ways to de-risk so we expect to see more buy-out solutions being offered in 2012," JLT said.